The length, volume and distribution of CT values in the anatomical structures are the fundamental prerequisites for quantitative analysis of CT images in the maxillofacial region. The purpose of this investigation is to analyze the effect of the neighboring anatomical structures on these morphometric values.1. Length of Anatomical Structures.The length involved in bone and soft tissue structures of 14 cadavers were measured in both cephalometric and CT images. The maximum width and height of the maxillary sinus obtained from CT images are well correlated to those from cephalograms. The cortical bone thickness of the mandible measured in the CT images are 10-30% less than those in cephalograms. The mucosal thickness of the palate measured in the CT images are about 20% less than that actually measured.2. Distribution of CT Value in ParotidA parotid gland was carefully removed from a cadaver with 32 teeth normally erupted and was placed back after wrapped with a sheet of paraffin wax. CT scan was performed for the parotid gland in the cadaver in situ and also in a water phantom. Average CT value in the axial CT image at the cervival plane of the maxilla was equivalent to that of water. However, the CT values were higher in the posterior portion (close to the mastoid process) and lower in the anterior portion (posterior to the madibular ramus) in the gland than those measured in the images of the gland in water.The CT profile in the coronal plane showed higher CT values for upper portion and lower CT values for lower portion of the gland than those obtained from the images in water. The mesio-lateral profile in the mid-plane of the coronal section indicated that CT values close to the madibular ramus were higher in the 1-2mm length than those measured in the gland in water.3. Volume of Salivary GlandThe volume estimated from CT images of the cadaver was about 30% larger for both parotid and submandibular glands than those actually measured for the extracted glands.